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/*
* Winnov WNV1 codec
* Copyright (c) 2005 Konstantin Shishkov
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/**
* @file wnv1.c
* Winnov WNV1 codec.
*/
#include "avcodec.h"
#include "common.h"
typedef struct WNV1Context{
AVCodecContext *avctx;
AVFrame pic;
int shift;
/* bit buffer */
unsigned long bitbuf;
int bits;
uint8_t *buf;
} WNV1Context;
/* returns modified base_value */
static inline int wnv1_get_code(WNV1Context *w, int base_value)
{
int v = 0;
if (w->bits < 16) { /* need to fill bit buffer */
w->bitbuf |= LE_16(w->buf) << w->bits;
w->buf += 2;
w->bits += 16;
}
/* escape code */
if ((w->bitbuf & 0xFF) == 0xFF) {
w->bitbuf >>= 8;
w->bits -= 8;
if (w->bits < 16) { /* need to fill bit buffer */
w->bitbuf |= LE_16(w->buf) << w->bits;
w->buf += 2;
w->bits += 16;
}
v = w->bitbuf & (0xFF >> w->shift);
w->bitbuf >>= 8 - w->shift;
w->bits -= 8 - w->shift;
return v << w->shift;
}
/* zero code */
if (!(w->bitbuf & 1)) {
w->bitbuf >>= 1;
w->bits--;
return base_value;
}
/* reversed unary code and sign */
while (w->bits && w->bitbuf & 1) {
w->bitbuf >>= 1;
w->bits--;
v++;
}
w->bitbuf >>= 1;
w->bits--;
if(w->bitbuf & 1)
v = -v;
w->bitbuf >>= 1;
w->bits--;
v <<= w->shift;
return base_value + v;
}
static int decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
WNV1Context * const l = avctx->priv_data;
AVFrame * const p= (AVFrame*)&l->pic;
unsigned char *Y,*U,*V;
int i, j;
int prev_y = 0, prev_u = 0, prev_v = 0;
if(p->data[0])
avctx->release_buffer(avctx, p);
p->reference = 0;
if(avctx->get_buffer(avctx, p) < 0){
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
p->key_frame = 1;
l->bitbuf = 0;
l->bits = 0;
l->buf = buf + 8;
if (buf[2] >> 4 == 6)
l->shift = 2;
else {
l->shift = 8 - (buf[2] >> 4);
if (l->shift > 4) {
av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
l->shift = 4;
}
if (l->shift < 1) {
av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
l->shift = 1;
}
}
Y = p->data[0];
U = p->data[1];
V = p->data[2];
for (j = 0; j < avctx->height; j++) {
for (i = 0; i < avctx->width / 2; i++) {
Y[i * 2] = wnv1_get_code(l, prev_y);
prev_u = U[i] = wnv1_get_code(l, prev_u);
prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
prev_v = V[i] = wnv1_get_code(l, prev_v);
}
Y += p->linesize[0];
U += p->linesize[1];
V += p->linesize[2];
}
*data_size = sizeof(AVFrame);
*(AVFrame*)data = l->pic;
return buf_size;
}
static int decode_init(AVCodecContext *avctx){
WNV1Context * const l = avctx->priv_data;
l->avctx = avctx;
avctx->pix_fmt = PIX_FMT_YUV422P;
return 0;
}
AVCodec wnv1_decoder = {
"wnv1",
CODEC_TYPE_VIDEO,
CODEC_ID_WNV1,
sizeof(WNV1Context),
decode_init,
NULL,
NULL,
decode_frame,
CODEC_CAP_DR1,
};
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